Nitrate compounds can be found in water supplies and, at elevated levels, can cause gastric problems related to nitrosamine in adults and can cause methemoglobinemia in infants. Drinking water standards typically include maximum allowable concentrations of nitrate compounds in public drinking water.
Nitrate compounds can also be found in low levels in biological tissue and, in particular, wound tissue. Nitric oxide synthase (NOS) produces nitric oxide (NO) in the tissue. The NO has a half-life of about 5 seconds in biological tissues. NO is normally metabolized to stable NO-related compounds (e.g., nitrate and nitrite compounds), which may be assayed in urine, plasma, tissue, wound fluid, or other specimens from a patient. The level of nitrate or nitrite compounds in a specimen can serve as an indicator of the level of NO synthesis in a patient. Below a threshold level of NO in a patient, normal wound repair is not achieved, resulting in a chronically non-healing wound or ulceration.
There is a need for simple, sensitive methods for measuring NO-related compounds in a sample.